1. Technical Field
The present invention relates to a liquid ejection head, a piezoelectric element, a piezoelectric actuator, and a liquid ejecting apparatus.
2. Related Art
The liquid ejection head is used for, for example, an ink jet printer and the like as a component of a liquid ejecting apparatus. In this case, the liquid ejection head is used for ejecting and flying small ink droplets. This makes it possible for an ink jet printer to perform printing by attaching the ink to a medium, such as paper.
In general, the liquid ejection head has an actuator that applies pressure to liquid in order to eject the liquid from a nozzle. Mentioned as such an actuator is one having a piezoelectric element, for example. Mentioned as the piezoelectric element of the actuator is one having a structure in which a piezoelectric material demonstrating an electromechanical conversion function, e.g., a piezoelectric body containing crystallized piezoelectric ceramics, is sandwiched between two electrodes. Such a piezoelectric element can be transformed by the application of a voltage by the two electrodes, and the actuator can be operated in a bending vibration mode, for example, utilizing the transformation.
As the piezoelectric material for use in such an application, the piezoelectric properties, such as electromechanical conversion efficiency, are preferably high. Since the properties are excellent as compared with other materials, lead zirconate titanate (PZT) materials have been researched and developed. In recent years, however, the use of materials with a lower environmental load has been demanded. Thus, the development of, for example, a piezoelectric material of a perovskite oxide with a small lead content has been advanced.
Mentioned as ceramic materials having theoretically high piezoelectric properties are Bi oxides, for example, and, BiFeO3 (BFO) is considered as the most promising candidate for the materials under the present circumstances.
However, BFO has a problem in that the insulation properties are low and the leakage current is high. Moreover, BFO also has a problem in that high voltage resistance is required because the coercive electric field is high and a high voltage needs to be applied for driving when used as a piezoelectric body.
Therefore, a BFO material in which a leakage current is suppressed by replacing some elements constituting the BFO has been proposed in, for example, JP-A-2009-231482.